Control system for traction transmission and hydraulic motor used therein

ABSTRACT

A control system ( 100 ) for traction transmission has at least two multi capacity motors (M 1 , M 2 ), which are adapted to rotate a vehicle&#39;s wheels (J 1 , J 2 ) and which multi capacity motor (M 1 ) is arranged to rotate a traction wheel (J 2 ), and the multi capacity motor (M 2 ) is arranged to rotate another traction wheel (J 1 ), whereby motor parts (M 1a  and M 2a ) of partial rotational volumes of the multi capacity motors (M 1 , M 2 ) can be connected in series, whereby the anti-slip is on.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority on Finnish App. No. 20075057, filed Jan. 26, 2007, and Finnish App. No. 20075400, filed Jun. 1, 2007, the disclosures of which are incorporated by reference herein.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

The invention concerns a control system for traction transmission and a hydraulic motor used therein.

Known in the state of the art are vehicle traction transmission solutions, in which hydraulic motors are used. Such hydraulic motor solutions are known in the state of the art, where such separate motors are used at the driving wheels, which can be controlled independently of each other. However, a persistent drawback in the known vehicle solutions is the uncontrolled slip situation, where a traction wheel slips, and it has not been possible to transmit power in an advantageous manner to the other traction wheels. The present application presents a new traction transmission solution, wherein two traction wheels can be connected in series in order to carry out an anti-slip function. The application preferably uses such a control system for the traction transmission, where such radial piston motors are used at the traction wheels, which are multi volume motors, whereby in a slip situation the motors can be connected at other motor parts in series in relation to one another.

There are also hydraulic motor requirements in traction transmission, which would need such a hydraulic motor structure, where it is possible to change the speed of rotation and the related moment or torque of a pump-operated hydraulic motor by the same pump output, which supplies the system. There are different device drives, where the driving wheel or traction wheel begins slipping undesirably. For said problems there ought to be such a hydraulic motor, which when placed in a hydraulic system would function as a motor where slipping would be prevented. Thus, the objective is a traction transmission system and a hydraulic motor, where, for example, at the so-called full rotational volume, that is, at the slower speed, the highest moment is achieved and with the same output another operating mode can be controlled, where, for example, at the hydraulic motor's ½ rotational volume a higher speed of rotation is achieved for the traction wheel along with a lower moment. In a hydraulic motor, for example, ½ rotational volume parts can be connected purely in series with another multi capacity hydraulic motor, whereby slipping of the multi capacity hydraulic motor is prevented in a series connection of the concerned motors.

SUMMARY OF THE INVENTION

This application also presents a new type of piston hydraulic motor, preferably a radial piston hydraulic motor, which allows at least two different operating modes; an operating mode, where a hydraulic motor operates at the lowest speed of rotation and at the highest moment and where the entire motor volume is full volume, whereby all pistons of the radial piston hydraulic motor are in operation at the full working pressure produced by the pump, and a partial volume operating mode, where the number of pistons working at each time is reduced, whereby the motor's speed of rotation correspondingly increases and the moment of the hydraulic motor is reduced. With a constant pump output different speeds and moments are achieved as well as at least two different speeds and different moments related to these. According to the invention, the hydraulic motor can be controlled from partial rotational volume to full rotational volume according to pressure detection and the resulting control.

As the multi capacity motor the invention preferably uses a radial piston hydraulic motor, where the piston body comprises piston-type cylinders and pistons in these. To each piston a presser wheel is connected, which is adapted to press against a cam ring. The cylinders in the piston body are located radially. In one embodiment, the piston body proper is in a fixed non-rotating position, as is the shaft of the hydraulic motor. On the shaft a distributor is located, through which hydraulic oil is distributed step by step to each piston and which rotates with the casing, which is rotated by the rotated cam ring. According to the invention, the shaft has a bore, in which there is a control spindle. The control spindle comprises pistons or necks or broadened parts, the function of which is to close and open oil channels. Thus, by moving the spindle one pressurized oil channel is opened and closed. In one embodiment the device solution thus comprises two pressurized inlet channels A₁ and A₂ and one outlet channel A₃, A₄ for the hydraulic motor. When the direction of rotation of the hydraulic motor is changed, the pressurized medium is changed to arrive through the channels A₃, A₄ and the discharging flows will take place through the two inlet channels A₁ and A₂.

In the following, the invention will be described by referring to some advantageous embodiments of the invention shown in the figures of the appended drawings, but there is no intention to limit the invention to these alone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows the hydraulic diagram of the control system for traction transmission according to the invention. The system comprises halves X₁ and X₂, which are identical and similar to one another. The halves X₁ and X₂ may be connected to each other by connecting channels D₁ and D₂, which comprise shut-off valves V₆ and V₇.

FIG. 1B shows the hydraulic diagram of the control system of FIG. 1A at its system half X₁, which is similar to the system half X₂ in the embodiment shown in FIG. 1A. In the phase shown in FIG. 1B, the anti-slip is not on, and the motor parts M_(1a) and M_(2a) are not series-connected.

FIG. 2 shows the control phase following after FIG. 1B, and here the valve V₁ connects the motor's M₁ motor part M_(1a) with the motor's M₂ motor part M_(2a), whereby a series connection is brought about between said motors and the anti-slip is on; motor part M_(1b) and motor part M_(2b) are in working operation. Arrows show the oil flow direction of the oil made to flow by the pump P₁.

FIG. 3 shows an anti-slip situation, where motor M₂ has moved over to partial volume, where the motor parts M_(1a) and M_(2a) are in series. Motor part M_(1b) is in working operation and motor part M_(2b) is plugged and thus disconnected.

FIG. 4 shows an operating mode, where the motor parts M_(1a) and M_(2a) are in series and the motor part M_(1b) is on while the motor part M_(2b) is off and in a loop R. In the embodiment shown in FIG. 4, the valve V₃ is not affected, so the control pressure is not admitted into channel Y₂, and the spindle of valve V₅ is raised by the effect of the spring force of a spring, so that valve V₅ is in the position shown in FIG. 4, in which motor M₂ is at partial volume.

FIG. 5 shows a so-called 25% working volume mode; motor part M_(1a) is in series with motor part M_(2a); motor part M_(1b) is in loop R and in a non-working state and, correspondingly, motor part M_(2b) is in loop R and in the non-working state.

FIG. 6 shows a start-up situation concerning motor M₂.

FIG. 7A shows the solution of FIG. 6 as regards a spindle K. FIG. 7A shows the initial situation and FIG. 7B shows the final situation.

FIGS. 8A and 8B are two different lengthwise cross-sectional views of a multi capacity hydraulic motor according to the invention used in the vehicle and traction transmission system presented above in order to show the channels.

FIG. 9 shows how the control spindle K is moved to a position, where another rotational volume is implemented for the piston hydraulic motor.

FIG. 10 is a view in principle of an embodiment of a piston hydraulic motor, where the shaft rotates, but the motor casing is non-rotating and the shaft is rotated. The solution for forming a multi capacity motor is the same, that is, as has been described in connection with the earlier figures.

FIG. 11 is a schematic view of the hydraulic system of the motor according to FIGS. 8A and 8B.

FIG. 12 shows a piston hydraulic motor in the anti-slip regulation of a harvester.

FIG. 13 is a cross-sectional view of a radial piston hydraulic motor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A shows a control system 100 for the traction transmission of; for example, a forestry machine, a tractor, an all-terrain vehicle or some other such vehicle T₁. The control system 100 is preferably a hydraulic control system and preferably a closed system. The system according to the figure comprises halves X₁ and X₂ of the control system for the traction transmission, which halves are identical and similar to one another in the figure. As is shown in the figure, pumps P₁ produce a pressurized medium and the pumps are rotated by a diesel engine, which is not shown. Pumps P₁ may be coaxial and driven by a diesel engine, and the pressure produced by the pumps can be controlled separately at each pump P₁ when required in order to control the speed of vehicle T₁. However, a common control is usually sufficient. As is shown in FIG. 1A, the halves X₁ and X₂ are connected to each other through pipe fittings D₁ and D₂, which comprise shut-off valves V₆ and V₇, whereby the system halves X₁ and X₂ can also be connected in connection with each other. There are four traction wheels in the vehicle. Such an embodiment is also possible within the scope of the invention, where a series connection is made between the motors M_(1a) and M_(2a), which are located in different parts of the vehicle T₁ in different halves X₁ and X₂. When the direction of travel D of vehicle T₁ is changed, the direction of rotation of pumps P₁ is changed.

The invention is described in FIG. 1B and it shows one half of the control system; half X₁. The half X₁ is used to control the front and rear wheels J₁ and J₂ of one half of the vehicle. The half X₂ is similar and it is used to control the front and rear wheels J₁ and J₂ of the other half of the vehicle. Thus, the vehicle is one with four-wheel drive.

As is shown in FIG. 1B, the direction of travel of vehicle T₁ is indicated by an arrow D in this figure. Pump P₁ produces a pressure in the system 100. As is shown in FIG. 1B, the pressurized medium is conducted from pump P₁ as arrows indicate in the embodiment shown in the figure into line a₁ and further to the motor M₁, which is a multi capacity motor and, for example, a radial piston hydraulic motor of a type to be presented later, the shaft of which is in a fixed position or the shaft is rotated. Both embodiments are possible. In the figure, the internal structure of the motors M₁ and M₂ are delimited as shown by dashed lines. As is shown in FIG. 1B, in the working phase shown in FIG. 1B the pressurized medium is thus brought from pump P₁ into line a₁ and further through one inlet B₁ to the multi capacity motor M₁, from which it is conducted as shown in the figure through line n₁ to the motor part M_(1a) of multi capacity motor M₁ and through line n₂ to an interior valve V₄ in motor M₁ and further through this to the motor part M_(1b) of the multi capacity motor. From motor M₁ there are two return lines b₃ and b₄ leading out.

As shown in FIG. 1B, from line a₁ there is a branch line a₂ for pressurized hydraulic oil further to valve V₁ and through branch line a₃ and through inlet F₂ to an interior valve V₅ in the other multi capacity motor M₂. The inlet connection for valve V₅ is indicated by reference number F₂.

Motors M₁ and M₂ are similar multi capacity motors. From multi capacity motor M₂ there is an outlet B₂ into line b₁ and back to pump P₁ in a closed circulation, when valve V₁ is in the position shown in FIG. 1B.

In the embodiment shown in FIG. 1B and in the operating mode shown in FIG. 1B, motor M₁ has one pressure line a₁ leading in and two return lines b₃ and b₄ leading out. Motor M₂ comprises two pressure lines a₃ and a₄ leading in and one outlet B₂ and a return line b₁ connected to this and leading out. The system preferably comprises in motors M₁ and M₂ inbuilt control components V₄, V₅, preferably valves, which comprise a control component for the oil flow, preferably a spindle K, 51.

In the phase shown in FIG. 1B, motors M₁ and M₂ are at the full rotational volume, whereby they will have the maximum moment and minimum speed of rotation. In the phase shown in FIG. 1B, valves V₅, V₄, V₃ and V₂ are trimmed, so to speak, that is, their valve spindles are moved by the solenoid against the spring force of the spring J at the end of the spindle into a position allowing the flow to pass through.

Valve V₄ is trimmed against the spring force of spring J by a supply pressure from line b₄, when the valve V₂ is active. Hereby the solenoid of valve V₂ has moved the spindle of valve V₂ to a position, where pressurized medium is allowed through valve V₂ to the end of the control spindle of valve V₄, whereby valve V₄ is in the position shown in FIG. 1B.

Correspondingly, when valve V₁ is in the position shown in FIG. 1B, pressurized medium is allowed from pump P₁ through line a₂ and through valve V₁ into line a₄ and through a branch point c₁ in line a₂ into line a₃ and further to the multi capacity motor M₂ into its motor part M_(2b), which implements the partial rotational volume, for example, the ½ rotational volume.

Valve V₅ is trimmed by supply pressure from line a₄, when valve V₃ is active, as shown in the figure. Hereby the valve spindle in valve V₃ is pressed against the spring force of spring J into a position, where control pressure is allowed through valve V₃ to the end of the control spindle of valve V₅ and the valve V₅ is thus moved against the spring force of its valve spring J to the position shown in FIG. 1B, where motor part M_(2b) is also on and receiving working pressure and motor M₂ is at the full rotational volume according to FIG. 2.

As shown in FIG. 1B, line b₄ is connected through valve V₁ to line b₂ and line b₂ is connected to the return line b₁ of pump P₁. Motors M₁ and M₂ are not connected in series, so the anti-slip function is not on.

In the phase shown in FIG. 1B, the line b₄ from outlet A1 of motor part M_(1a) of motor M₁ is connected to the return line b₂ through valves V₁. The pressure line a₂ is connected through valve V₁ to line a₄ and to the inlet of motor part M_(2a) of motor M₂. The motor parts M_(1a) and M_(2a) are not connected in series, so the anti-slip function is not on.

The pressure from line b₄ is conducted through line a′₁ to spindle K of valve V₄ and further through it to valve V₂ and further through it, if valve V₂ is in the position shown in FIG. 1B, that is, activated, to the end of spindle K of valve V₄ to control spindle K to a position, which is shown in FIG. 1B, that is, to the trimmed position against the spring force of spindle K of valve V₄.

At the valve V₅ the control is of a similar kind. Control pressure is brought to the end of the spindle of valve V₅ from line a₄ and it is circulated through the spindle of valve V₅ further to valve V₃, which allows the control pressure to pass through it when the valve V₃ is in the activated position shown in FIG. 1B, whereby the control pressure is allowed as shown in the figure to the end of spindle K of valve V₅ to control it to the position shown in FIG. 1B. In the phase shown in FIG. 1B, the multi capacity motors M₁ and M₂ are not in a series-connection and the anti-slip function is not on.

FIG. 2 shows a phase in the operation where motors M₁ and M₂ are connected in series at their motor parts M_(1a) and M_(2a) and connected in parallel, so to speak, at their motor parts M_(1b) and M_(2b). An operating volume of 75% is hereby achieved.

The series connection and parallel connection shown in FIG. 2 are achieved in such a way that valve V₁ is moved to the position shown in FIG. 2. Hereby the line b₄ from the multi capacity motor M₁ is connected through valve V₁ to line a₄ and to the multi capacity motor M₂ and the motor parts M_(1a) and M_(2a) in the multi capacity motors M₁ and M₂ are connected in series in relation to each other, and hereby slipping of the traction wheels J₁, J₂ is prevented. In the embodiment in FIG. 2, motors M₁ and M₂ are thus in a series-connected state as regards the partial volumes M_(1a) and M_(2a), and the anti-slip function is hereby active. Hereby the speed of the multi capacity motors M₁ and M₂ increases and the moment is reduced. In the phase shown in FIG. 2, the motor parts M_(1b) and M_(2b) as well as the partial volumes, such as ½ volumes, are also in use.

If in the phase shown in FIG. 2 the front wheel J₁ begins slipping, the pressure in line a₄ will be reduced. When the force caused by the pressure is reduced below the spring force of spring J of valve V₅, valve V₅ will move motor M₂ to partial volume and will close the pressure line F₂, as happened in the way shown in FIG. 3.

Thus, when wheel J₁ begins slipping, the pressure of the medium will disappear from line a₄. When the pressure is reduced from connection a′2, the pressure is also reduced through valve V₃ from connection Y₂, as a result of which the spring force of valve V₅ will win over the concerned pressure force from the valve's V₅ connection Y₂. The spindle will hereby move and the inlet F₂ will close, and as a result of this the pressure in line a₁ begins growing and motor M₁ will have a higher pressure, whereby it tries to move at a higher moment the traction wheel J₂ connected to motor M₁.

FIG. 4 shows a phase in the control, where motors M₁ and M₂ are connected in parallel and in series. A total working volume of 50% is achieved in the connection. In the embodiment shown in FIG. 4, motor parts M_(1a) and M_(2a) are connected in series and motor part M_(1b) is in operation and motor part M_(2b) is out of operation and in a so-called closed circulation or loop.

FIG. 5 shows the system in a phase of operation, where motor part M_(1b) is entirely disconnected and it circulates oil in a so-called loop R, whereby the concerned oil is so-called low-pressure oil, and it causes hardly any loss of the coefficient of efficiency. Motor part M_(1a) is on and connected in series through pipe fitting b₄ and a₄ to motor part M_(2a) of motor M₂. Motor part M_(2b) is disconnected and it circulates oil in loop R through the spindle of valve V₅ in a manner corresponding with what took place with valve V₄. Motor parts M_(1a) and M_(2a) are working and a calculated share of 25% of the volume is in operating use. The connection in question is achieved in such a way that valve V₂ is not activated and thus it closes the arrival of control pressure to the end of the spindle of valve V₄, whereby spindle V₄ is in a position where the motor part M_(1b) of multi capacity motor M₁ is in a so-called loop R away from the oil circulation and low-pressure oil circulates through spindle K of valve V₄ and through the cylinders of motor part M_(1b). Correspondingly, valve V₅ of motor M_(2b) is in a corresponding position and arrival of pressurized oil to motor part M₂ as shown in FIG. 5 is prevented. Valve V₃ is hereby non-activated, so to speak, and no pressurized medium is allowed to the end of the spindle V₅ and the spring J in valve V₅ has moved the valve spindle K to the position shown in FIG. 5.

FIG. 6 shows a so-called start-up situation, that is, the initial run situation. Spindle K of valve V₅ is in the position shown in FIG. 6, whereby motor M₂ is not at full volume as it should be when the vehicle starts moving. However, in the connection F₂ to spindle K of valve V₅ a sensor line S₁ is installed, from which a so-called pressure data identification will reach valve V₅ through valve V₃ when valve V₃ is activated. Hereby, when the pressure increases in inlet line F₂ to valve V₅, the pressure data is transferred through line S₁ and to valve V₃ and through this when valve V₃ is activated to the end of spindle K of valve V₅ through line Y₂. Valve V₅ will hereby move to a position, where motor M₂ is connected to full volume, that is, motor parts M_(2a) and M_(2b) are both in operating use, whereby the maximum moment is also achieved, which is advantageous when starting.

FIG. 7A shows implementation of the above-mentioned start-up situation in the area of spindle structure K of valve V₅. Through inlet F₂ the control pressure is conducted by way of valve spindle K to valve V₃ and further, as valve V₃ is activated according to the figure, the pressure is transferred through line Y to the end of spindle K. The spindle K is hereby moved to the position shown in FIG. 7B. As shown in FIG. 7B, the control pressure has moved spindle K to a position where working pressure from line F₂ is admitted through spindle K further to the motor part M_(2b) of motor M₂. At the end of spindle K there is a spring J. Such an embodiment is also possible, where the spring force of spring J is replaced by the effective force of a pressurized medium, the spring or pressurized medium forming a biasing element.

FIGS. 8A and 8B show a piston hydraulic motor 10, which in the embodiment is a radial piston hydraulic motor. The motor 10 shown is suitable for use as a multi capacity motor M₁, M₂ in the hydraulic system 100 according to the invention for traction transmission. It has a rotating outer periphery 11, that is, a casing and a central shaft 12 in a fixed position. The body 13 surrounding the shaft in a fixed position contains cylinders 11 and pistons, which comprise presser wheels 14, which will rest against a wave-like cam ring 15 rotated by the pistons. A distributing valve 16 rotates with the casing 11 and it comprises peripheral millings and from these bores to the frontal face of the distributing valve, from which channels open to conduct the pressurized medium to a bank of cylinders Va₁, Va₂ (indicated schematically in FIG. 11) in order to produce a force at the right time through pistons in the working phase to the cam ring 15 in order to rotate this and the connected casing 11. To the pistons V in the working phase a pressurized medium, preferably hydraulic oil, is brought and from the pistons in the non-working phase the almost pressure-free medium, such as oil, is conducted through the distributor's, that is, the distributing valve's 16 frontal face to the distributor's outlet channel and further to the channels of the non-rotated shaft 12, to the outlet connection and further finally out of the hydraulic motor 10. When changing the pressurization with the directional control valve (not shown) between the motor inlet and outlet, the motor's direction of rotation is changed. The spindle is indicated by reference number 51 or K.

The radial piston hydraulic motor 10 comprises a cylinder body 13 and therein radial cylinders and in these pistons V and presser wheels 14. A rotating distributor 16 has a frontal face with bores connected to bores in the piston body 13. A pressurized medium, that is, the working pressure is brought through inlet channels A₁ and A₂, shown in FIG. 8B. Channel A₂ is a pressure channel, which conducts the pressurized medium as shown in the embodiment of FIG. 2 through bores in shaft 12 into a space P in between neck parts G₂, G₃ in the spindle 51 of control valve 50 and into channel F and further to the outer periphery of shaft 12 and further through grooves and bores in the distributor's side surface into the respective bore in piston body 13 in order to conduct pressurized medium in the right phase to the pistons V in the working phase and to remove the outgoing oil flow taking place from pistons V in the discharging phase from the pistons in the concerned phase. Some pistons are thus in the so-called non-working phase, whereby the pistons remove medium at a lower pressure, such as oil, from the piston space and further through the piston body's channel to the distributing valve 16 and further through its channels to the outlet channel B in shaft 12. Each piston V is in turn in the working phase and in turn in the non-working phase, that is, in the oil-removing phase. The pistons in the working phase press the presser wheels connected to the pistons with force against the wave-like opposite surface, that is, the cam ring 15, whereby the motor's 10 casing connected to the cam ring 15 will be rotated.

When the control valve's 50 central control spindle 51, K with its piston-like necks or broadened parts G₁, G₂, G₃ is in the position shown in FIGS. 8A and 8B, the return channel's oil flow at a lower pressure is conducted from the pistons, that is, the return oil to channel B₁ and to the space D in between the spindle's broadened parts G₁ and G₂ in the spindle cavity 52, such as a bore, from which the oil moves into channel F and further into the channel system of distributing valve 16 and further to the pistons V and cylinders V_(a2), which are at a lower pressure, which is non-working pressure. This is a so-called partial volume mode, for example, a ½ volume mode, whereby the motor has a higher speed of rotation and a lower moment than in the so-called full volume mode. Hereby the bank of cylinders/pistons V_(a2) is in a sense disconnected from operation and it circulates oil at an idle pressure in a loop formed by the closed circuit B₁, F.

FIG. 9 shows the control spindle moved to a position, where piston G₂ or the so-called neck is placed in between the channels F and B₁ and it closes the connection from channel B₁ to channel F, to which a connection is opened A₂ for the channel's pressurized oil flow. In the position of the control spindle shown in the figure, pressurized oil is conducted from channel A₂ to the left side of the piston G₂ or neck in the figure and further into channel F and further to the distributing valve and through this at full pressure to the pistons V_(a2) which are at a certain working pressure. The banks of piston-type cylinders V_(a1)+V_(a2) are hereby in operation for the oil brought at full pressure from pump P₁. The bank of piston-type cylinders V_(a1) for the pressurized oil brought through channel A₁ is always in operation.

The control spindle 51 or K of the actuator, that is, control valve 50 is controlled according to the pressure existing in channel A₁. If the pressure in channel A₁ falls below a certain critical value, the control valve will move under the influence of spring J to the position shown in FIG. 1 and the mode 1 is achieved according to FIG. 1, whereby only some pistons in bank V_(a1), for example, a half, will have working pressure, whereas the rest; bank V_(a2) will have a low pressure, the so-called idle pressure of the feedback of return circulation, whereby bank V_(a2) is not in operation in the actual sense.

If the pressure in channel A₁ increases, control spindle 51 is moved into the position shown in FIG. 2 by a pressure produced at the left-hand end of spindle 51. The function of the spring J located in between the right-hand end of the control spindle's 51 spindle cavity 52 and the spindle's neck G₁ is to act as a counter-force to the force generated by the control pressure. When choosing an operating mode for the multi capacity motor 10, the spindle 51 is thus moved with the aid of control pressure brought to the left-hand end (in the figure) of the spindle cavity 52 as shown in FIGS. 8A and 8B by arrows L₁ against the spring force of spring J.

In all operating modes, both at full rotational volume and at partial rotational volume, the bank of cylinders/pistons Va₁ in connection with working pressure channel A₁ is in operation at all times.

FIG. 11 shows a schematic view of the hydraulic system of the motor 10 shown in FIGS. 8A and 8B. Hydraulic oil is brought under a pressure along two channels A₁ and A₂ to the multi capacity motor 10. From the multi capacity motor 10 there is a loop or set of channels M₁, by which oil is circulated through the pistons at non-working pressure inside the motor. As shown in the figure, the system further comprises a pipe fitting C₁₀ or channel or other such to conduct control pressure to valve 50 from channel A₁, by which the operating mode of the multi capacity motor 10 can be controlled, in which partial rotational volume is carried out along with a pure connection in series of successive hydraulic motors when the concerned multi capacity motor tends to slip.

FIG. 11 also shows a directional control valve 70, which is controlled by a solenoid against the spring force of spring J₁₀. When the directional control valve section 70 a is on as shown in the figure, the pressure existing in line C₁₀ is detected and it is moved to actuator 50, preferably to the end of spindle 51 of the valve equipment, to affect the valve spindle against the spring force of spring J. When section 70 b of the directional control valve 70 is turned on when no control voltage is supplied to the solenoid, the connection of pressure line C₁₀ to the spindle 51 is closed, whereby the spring J of actuator 50 will move the spindle to a position, where section V_(a2) is closed and the motor is operated at a higher speed.

FIG. 10 is a schematic view of another type of hydraulic motor 10, which operates in the same manner as the presented multi capacity motor and in this embodiment comprises similar structural parts as in the earlier figures. An essential difference in this embodiment is that shaft 12 with its piston body 13 is rotating. The motor's 10 actual casing 11 and the connected distributor 16 or distributing valve and cam ring 15 are non-rotating. In the full volume solution Va₁+Va₂ oil at working pressure is conducted to the piston body's all pistons/cylinders Va₁, Va₂ through channels A₁ and A₂, by way of the distributor 16 and the motor's 10 non-rotating casing 11. The equipment arrangement and the operation are the same as in the embodiment in the FIGS. 1, 2 and 3 shown above, where the radial piston hydraulic motor's casing 11 and the distributor 16 are rotated and in which embodiment the shaft 12 and piston body 13 are in a fixed position. In the embodiment shown in FIG. 4, the hydraulic motor's 10 casing 11 and the connected distributing valve 16 are non-rotating. Shaft 12 of motor 10 and the connected piston body 13 are rotating. The operation of the embodiment is the same as the operation of the embodiment of the hydraulic motor presented by the earlier FIGS. 1, 2 and 3.

FIG. 12 shows a multi capacity motor 21 adapted to the anti-slip regulation of timber feeding. The multi capacity motor 21 is located to supply timber together with another multi capacity motor structure 24, which is placed in parallel with said first motor 21. The motor's 21 bank of cylinders/pistons Va₁ is connected in series with a conventional hydraulic motor 3 and the other multi capacity motor's 24 bank of cylinders/pistons Va₁ is in series with another conventional hydraulic motor 4. In both motors, the multi capacity motor's 21, 24 bank of cylinders/pistons Va₂ is connected directly to a pump channel A₂ and to a pump P₁, whereby as regards bank Va₂ the connection is a connection in parallel with motors 21, 24. When in timber-feeding the motor tends to slip at full rotational volume Va₁+Va₂, bank Va₂ is disconnected with the aid of the arrangement shown in FIG. 3.

FIG. 13 is an illustrating presentation of radial cylinders and pistons relating to the state of the art. In the embodiment shown in the figure, there are eight pistons and thus eight cylinders, and thus the bank of pistons/cylinders Va₁ may comprise, for example, four pistons and the connected cylinders and, correspondingly, bank Va₂ may comprise four pistons and cylinders. FIG. 13 is a cross-sectional view of a radial piston hydraulic motor, which comprises eight hydraulic cylinders and the connected pistons.

In the Va₁+Va₂ mode, hydraulic oil under working pressure is conducted to all pistons, which are in the working phase. In the Va₁ mode, hydraulic oil at working pressure is only conducted to bank Va₁, whereas to bank Va₂ in said mode only hydraulic oil at a low pressure, not oil at working pressure is conducted to its pistons, even to those in the working phase. However, those pistons, which are in the working phase at each time under the working pressure of pump P₁, may vary in one and the same hydraulic motor.

In this application, the word channel is understood as meaning pipes, hoses, bores and other such connections. In this application, the word mode or operating mode or partial or full rotational volume is used for the multi capacity motor's certain banks of cylinders and their connected pistons. The rotational volume can be full rotational volume Va₁+Va₂ or partial rotational volume Va₁. 

1. A traction transmission and control system comprising: a first radial-piston motor operatively connected to drive a first vehicle wheel, the first radial-piston motor comprising: a central shaft with a plurality of piston bodies with a plurality of pistons, one of said plurality of pistons mounted in each piston body for radial motion, a plurality of presser wheels, one of said plurality of presser wheels mounted on each piston, a casing surrounding the central shaft, the central shaft and the casing mounted for relative rotation, a cam ring having a wave-shaped surface mounted to the casing so that the presser wheels mounted to the pistons bear on the cam ring wave-shaped surface, wherein the plurality of piston bodies are divided into a first group of piston bodies and a second group of pistons bodies, portions of the central shaft forming a first supply channel which is connected to the first group of piston bodies by a distributer mounted to rotate, portions of the central shaft forming a second supply channel which is connected to the second group of piston bodies by the distributer, a first actuator arranged to open and close the second supply channel with respect to the second set of piston bodies; a second radial-piston motor operatively connected to drive a second vehicle wheel, the second radial-piston motor comprising: a central shaft with a plurality of piston bodies with a plurality of pistons, one of said plurality of pistons mounted in each piston body for radial motion, a plurality of presser wheels, one of said plurality of presser wheels mounted on each second motor piston, a casing surrounding the second motor central shaft, the second motor central shaft and the casing mounted for relative rotation, a cam ring having a wave-shaped surface mounted to the second motor casing so that the second motor presser wheels mounted to the second motor pistons bear on the cam ring wave-shaped face, wherein the plurality of second motor piston bodies are divided into a third group of pistons bodies and a fourth group of piston bodies, portions of the second motor central shaft forming a third supply channel which is connected to the third group of piston bodies by a distributer mounted to rotate, portions of the second motor central shaft forming a fourth supply channel which is connected to the fourth group of piston bodies by the second motor distributer, a second actuator arranged to open and close the fourth supply channel with respect to the fourth set of piston bodies; a series connection between the first group of piston bodies and the third group of piston bodies, the series connection placing the first group of piston bodies in series with the third group of piston bodies, so that the third supply channel is connected to receive hydraulic fluid which has passed through the first supply channel and the first group of piston bodies, so forming an anti-slip connection between the first vehicle wheel and the second vehicle wheel; wherein the first actuator and the second actuator are connected to be controlled according to a pressure existing in the series connection, so that below a selected pressure in the series connection the second group of piston bodies is closed off from the second supply channel and the fourth group of piston bodies is closed off from the fourth supply channel.
 2. The traction transmission and control system of claim 1 wherein the first motor central shaft is connected to the first vehicle wheel and the first actuator is mounted in said central shaft, with portions of the central shaft forming a bore having a first end at which is mounted a spring and a second end in actuation pressure receiving relation to the series connection and the first actuator further comprises a spindle mounted for movement in the bore; and wherein the second motor central shaft is connected to the second vehicle wheel and the second actuator is mounted in said second motor central shaft, with portions of the second motor central shaft forming a bore having a first end at which is mounted a spring and a second end in actuation pressure receiving relation to the series connection, and the second actuator further comprises a second spindle mounted for movement in the second motor bore.
 3. The traction transmission and control system of claim 1 further comprising a valve positioned in the series connection and arranged to break the series connection between the first group of piston bodies and the third group of piston bodies by connecting the first group of piston bodies to a return line of a pump, and by connecting the third group of piston bodies to a supply line from the pump.
 4. The traction transmission and control system of claim 2 further comprising a first shut-off valve arranged to shut off arrival of control pressure to the first actuator so the spring will move the spindle to thus close the first actuator, and a second shut-off valve arranged to shut off arrival of control pressure to the second actuator so the spring will move the spindle to thus close the second actuator.
 5. The traction transmission and control system of claim 4, wherein the fourth supply channel for supplying pressurized oil to the fourth group of piston bodies can be closed automatically, and the second actuator comprises a pressure connection to conduct control pressure to the second end of the spindle of the second motor through the second shut-off valve, whereby when the pressure in connection to the fourth supply channel increases in the second end of the spindle to exceed a spring force of the spring the second actuator is opened wherein the second motor is connected for a full volume of pressurized medium to enter the fourth group of piston bodies.
 6. A traction transmission and control system comprising: a vehicle having a plurality of wheels; a hydraulic pump; a first multi capacity hydraulic motor having a first rotation volume connected to the pump, and a second rotation volume arranged to be connected to the pump through a first valve which is biased by a biasing element in a closed position, the first motor arranged to drive a first wheel of said plurality of wheels; a second multi capacity hydraulic motor having a third rotation volume connected in series with the first rotation volume so that oil from the pump passes through the first rotation volume and by way of a return line passes through the third rotation volume of the second motor, and the second multi capacity hydraulic motor having a fourth rotation volume arranged to be connected to the pump through a second valve which is biased by a biasing element in a closed position, the second motor arranged to drive a second wheel of said plurality of wheels; and wherein the first valve and the second valve are connected to be held opened by oil pressure in the return line between the first rotation volume and the third rotation volume, and to close when pressure in the return line falls below a selected value.
 7. The traction transmission and control system of claim 6 wherein the first multi capacity hydraulic motor and the second multi capacity hydraulic motor are radial piston hydraulic motors, and each of the first rotation volume, the second rotation volume, the third rotation volume, and the fourth rotation volume are formed by a plurality of piston bodies with a plurality of pistons, one of said plurality of pistons mounted in each piston body for radial motion.
 8. The traction transmission and control system of claim 7 wherein the first motor has a central shaft which is connected to the first wheel and the first valve is mounted in said central shaft with portions of the central shaft forming a bore having a first end at which is mounted a spring forming the biasing means and the bore having a second end in actuation pressure receiving relation to the return line, and wherein a spindle is mounted for movement in the bore as part of the first valve, and wherein the second motor has a central shaft which is connected to the second wheel and the second valve is mounted in said second motor central shaft, with portions of the second motor central shaft forming a bore having a first end at which is mounted a spring forming the biasing means and having a second end in actuation pressure receiving relation to the return line, and wherein a spindle is mounted for movement in the bore as part of the second valve. 